/*========================== begin_copyright_notice ============================

Copyright (C) 2017-2023 Intel Corporation

SPDX-License-Identifier: MIT

============================= end_copyright_notice ===========================*/

//
/// GenXVisaRegAlloc
/// ----------------
///
/// GenXVisaRegAlloc is a function group pass that allocates vISA registers to
/// LLVM IR values.
///
/// Before allocating registers, this pass does "extra coalescing", over and
/// above what GenXCoalescing does. Two otherwise independent live ranges that
/// are related by being an operand and the result of the same instruction (and
/// are the same type) get coalesced and thus allocated into the same register.
///
/// However, extra coalescing is not performed when the result of the
/// instruction is used in a non-alu intrinsic, to try and avoid the danger of
/// the jitter needing to add an extra move in the send.
///
/// Other than that, all this pass does is allocate a different vISA register to
/// each LiveRange.
///
/// The pass is also an analysis for GenXKernelBuilder to query to find out
/// what vISA register is allocated to a particular Value. In fact, the query
/// from GenXKernelBuilder can specify what type it wants the register to be,
/// and it is at that point that an alias is allocated if there is no existing
/// alias of the requested type.
///
/// Finally, there are callbacks in the analysis to generate the vISA variable
/// tables to put into the vISA file.
///
//===----------------------------------------------------------------------===//
#ifndef GENXVISAREGALLOC_H
#define GENXVISAREGALLOC_H

#include "FunctionGroup.h"
#include "GenX.h"
#include "GenXLiveness.h"
#include "GenXModule.h"

#include "vc/Support/BackendConfig.h"
#include "vc/Utils/GenX/RegCategory.h"

#include "Probe/Assertion.h"
#include "visaBuilder_interface.h"

#include <map>
#include <string>
#include <vector>
#include <unordered_map>

namespace llvm {

class Function;
class FunctionPass;
class raw_ostream;
class Type;
class Value;

ModulePass *createGenXGroupPrinterPass(raw_ostream &O,
                                       const std::string &Banner);

// GenXVisaRegAlloc : vISA virtual register allocator pass
class GenXVisaRegAlloc : public FGPassImplInterface,
                         public IDMixin<GenXVisaRegAlloc> {
public:
  inline static const char *Prefix[] = {"ERR", "V", "A", "P", "S", "T"};

  static StringRef categoryToString(vc::RegCategory Category) {
    if (static_cast<unsigned>(Category) >= std::size(Prefix))
      Category = vc::RegCategory::None;
    return accessContainer(Prefix, Category);
  }
  static void getAnalysisUsage(AnalysisUsage &Info);
  static StringRef getPassName() {
    return "GenX vISA virtual register allocator Wrapper";
  }

  // Reg : a virtual register
  class Reg {
  public:
    vc::RegCategory Category = vc::RegCategory::None;
    // Register ID. First value of it depends on count of predefined
    // variablse in category. F.e. for general var it is 32.
    unsigned Num = 0;
    // Pointer to register that is aliased by this register.
    Reg *AliasTo = nullptr;
    // Single linked list to store all aliases of real register.
    Reg *NextAlias = nullptr;
    genx::Signedness Signed = genx::DONTCARESIGNED;
    Type *Ty = nullptr;
    // Template, as bfloat not llvm-10 type
    bool IsBF = false;

    // log2 min alignment requested by user of register
    unsigned Alignment = 0;
    // String representation of register, mostly it is combination of
    // Category and Num
    std::string NameStr;
    // Attributes
    std::vector<std::pair<unsigned, std::string>> Attributes;
    // Pointer to VISA variable. It is set by CisaBuilder when it creates
    // VISA variables for all registers in RegMap.
    std::unordered_map<VISAKernel *, void *> GenVar;

    Reg(vc::RegCategory Category, unsigned Num, Type *Ty = 0,
        genx::Signedness Signed = genx::DONTCARESIGNED,
        unsigned LogAlignment = 0, Reg *AliasTo = nullptr, bool ArgIsBF = false)
        : Category(Category), Num(Num), AliasTo(AliasTo), Signed(Signed),
          Ty(Ty), Alignment(LogAlignment), IsBF(ArgIsBF) {
      IGC_ASSERT(vc::isRealCategory(Category));
      NameStr = (Twine(categoryToString(Category)) + Twine(Num)).str();
    }

    // Get VISA variable assigned to register.
    // Template T is just cast for return Type. Normally, we need to do an
    // assertion test here that required Var type is equal of real type in
    // GenVar.
    template <class T> T *GetVar(VISAKernel *F) {
      return reinterpret_cast<T *>(GenVar[F]);
    }

    // Set VISA variable for current register.
    void SetVar(VISAKernel *F, void *Var) { GenVar[F] = Var; }

    void addAttribute(unsigned AttrName, Twine AttrVal) {
      Attributes.push_back(std::make_pair(AttrName, AttrVal.str()));
    }

    bool canBeAliased() const {
      switch (Num) {
      // TODO: Make sure that only the right type is used for a reg and then
      // uncomment it below
      // case PreDefined_Vars::PREDEFINED_NULL:
      // case PreDefined_Vars::PREDEFINED_X:
      // case PreDefined_Vars::PREDEFINED_Y:
      // case PreDefined_Vars::PREDEFINED_GROUP_ID_X:
      // case PreDefined_Vars::PREDEFINED_GROUP_ID_Y:
      // case PreDefined_Vars::PREDEFINED_GROUP_ID_Z:
      // case PreDefined_Vars::PREDEFINED_TSC:
      // case PreDefined_Vars::PREDEFINED_FE_SP:
      // case PreDefined_Vars::PREDEFINED_FE_FP:
      // case PreDefined_Vars::PREDEFINED_HW_TID:
      case PreDefined_Vars::PREDEFINED_SR0:
      case PreDefined_Vars::PREDEFINED_CR0:
      // case PreDefined_Vars::PREDEFINED_CE0:
      // case PreDefined_Vars::PREDEFINED_DBG:
      // case PreDefined_Vars::PREDEFINED_COLOR:
      case PreDefined_Vars::PREDEFINED_MSG0:
        return false;
      default:
        return true;
      }
    }

    void print(raw_ostream &OS) const;
  };

  using RegPushHook = void (*)(void *Object, Reg &);
  using RegMap_t = std::map<genx::SimpleValue, Reg *>;
  using LRPtrVect = std::vector<genx::LiveRange *>;
  using LRCPtrVect = std::vector<const genx::LiveRange *>;
  void print(raw_ostream &OS, const FunctionGroup *FG) const override;

private:
  FunctionGroup *FG = nullptr;
  GenXLiveness *Liveness = nullptr;
  GenXNumbering *Numbering = nullptr;
  FunctionGroupAnalysis *FGA = nullptr;
  const GenXSubtarget *ST = nullptr;
  const GenXBackendConfig *BackendConfig = nullptr;
  const DataLayout *DL = nullptr;

  // pushReg callback that will be called once new register is created
  RegPushHook TheRegPushHook = nullptr;
  // Object that will be passed to hook, likely it is 'this' of hook owner.
  void *TheRegPushHookObject = nullptr;

  // Storage for all created registers. It is list because we use pointers
  // to stored registers, thus we need to non-reallocable storage.
  std::list<Reg> RegStorage;
  // Map from LLVM Value to pointer to register associed with it.
  RegMap_t RegMap;
  // List of pointers to predefined surface registers.
  std::vector<Reg *> PredefinedSurfaceRegs;
  std::vector<Reg *> PredefinedRegs;

  // Array of current indexes being assigned to new register.
  unsigned CurrentRegId[vc::numRegCategories()];

  struct RegAllocStats {
    const LRCPtrVect *getLRs(const FunctionGroup *FG) const;
    void recordLRs(const FunctionGroup *FG, const LRPtrVect &LRs);

  private:
    std::map<const FunctionGroup *, LRCPtrVect> LRs;
  } Stats;

public:
  explicit GenXVisaRegAlloc() {}
  void releaseMemory() override;
  bool runOnFunctionGroup(FunctionGroup &FG) override;

  std::list<Reg> &getRegStorage() { return RegStorage; }
  // Get the vISA virtual register for a value or nullptr if there is no
  // register associated with given value.
  Reg *getRegForValueOrNull(genx::SimpleValue V,
                            genx::Signedness Signed = genx::DONTCARESIGNED,
                            Type *OverrideType = nullptr,
                            bool IsBF = false) const;

  // Get the vISA virtual register for a value or create alias if there is no
  // register associated with given value.
  Reg *getOrCreateRegForValue(genx::SimpleValue V,
                              genx::Signedness Signed = genx::DONTCARESIGNED,
                              Type *OverrideType = nullptr, bool IsBF = false);

  // Get the vISA virtual register for a value (0 if none), ignoring type
  // and signedness so it can be a const method usable from print().
  Reg *getRegForValueUntyped(genx::SimpleValue V) const;

  // Get the signedness of a register.
  genx::Signedness getSigned(const Reg *R) const;

  // Set callback that will be called each time new register is created.
  // It is used in CisaBuilder when new aliases are created.
  void SetRegPushHook(void *Object, RegPushHook Callback) {
    TheRegPushHook = Callback;
    TheRegPushHookObject = Object;
  }

  void reportVisaVarableNumberLimitError(vc::RegCategory Category,
                                         unsigned ID) const;

  static unsigned getMaximumVariableIDForCategory(vc::RegCategory Category);

  static bool isVisaVaribleLimitExceeded(vc::RegCategory Category,
                                         unsigned CurrentID) {
    const auto IDLimit = getMaximumVariableIDForCategory(Category);
    return CurrentID > IDLimit;
  }

  // Create new register and push it in storage.
  // If RegPushHook was specified it will be called with created register as
  // parameter. Thus, all needed register's variables must be specified
  // at this moment, for example AliasTo.
  template <class... Args>
  Reg *createReg(vc::RegCategory Category, Args &&...args) {
    if (isVisaVaribleLimitExceeded(
            Category, vc::accessContainer(CurrentRegId, Category))) {
      reportVisaVarableNumberLimitError(
          Category, vc::accessContainer(CurrentRegId, Category));
    }
    auto NewID = vc::accessContainer(CurrentRegId, Category)++;
    IGC_ASSERT(vc::accessContainer(CurrentRegId, Category) != 0);
    RegStorage.emplace_back(Category, NewID, std::forward<Args>(args)...);
    Reg &R = RegStorage.back();
    if (TheRegPushHook)
      TheRegPushHook(TheRegPushHookObject, R);
    return &R;
  }

private:
  void getLiveRanges(LRPtrVect &LRs) const;
  void getLiveRangesForValue(Value *V, LRPtrVect &LRs) const;
  void localizeLiveRangesForAccUsage(LRPtrVect &LRs);
  void extraCoalescing();
  void allocReg(genx::LiveRange *LR);

public:
  // Add special RetIP argument.
  Reg *getRetIPArgument() const { return RetIP; }
  void addRetIPArgument();

private:
  unsigned CoalescingCount = 0;
  Reg *RetIP = nullptr;
};
using GenXVisaRegAllocWrapper = FunctionGroupWrapperPass<GenXVisaRegAlloc>;

namespace visa {
// Details of a type required for a vISA general register declaration
// or an indirect operand.
struct TypeDetails {
  const DataLayout &DL;
  unsigned NumElements = 0;
  unsigned BytesPerElement = 0;
  unsigned VisaType = ISA_TYPE_NUM;
  TypeDetails(const DataLayout &DL, Type *Ty, genx::Signedness Signed,
              bool IsBF = false);
};
} // end namespace visa

void initializeGenXVisaRegAllocWrapperPass(PassRegistry &);

} // end namespace llvm
#endif // ndef GENXVISAREGALLOC_H
